Vacuum control device for the displacement of an element between at least three positions

ABSTRACT

A vacuum control device comprises a casing in which are disposed at least two substantially parallel movable cups, the first cup being connected to the element to be displaced. Springs are interposed respectively between the two cups and between the second cup and a bottom end-wall of the casing. Two pipes or nipples connected to a vacuum source and to atmospheric pressure open into the casing respectively within the space located between the two cups and within the space located between the second cup and the casing end-wall.

This is a divisional of copending application Ser. No. 616,476, filedJune 1, 1984, U.S. Pat. No. 4,612,847.

This invention relates to a vacuum control device for the displacementof any element between at least three positions. The invention isprimarily applicable to the field of automotive vehicles in which thedevice serves to actuate a flap of an installation for heating orair-conditioning of the occupant compartment of a vehicle body.

In comparison with cable control devices, vacuum control devices offeran advantage in that the positional arrangement of the control unit onthe dashboard of a vehicle is independent of the position of the elementto be displaced, whereas this is not the case in a cable control system.A further advantage is that a lower effort is required in order tooperate a control unit of this type.

Furthermore, in the event of failure of the control unit, the element tobe displaced is automatically returned by means of restoring springs toa predetermined safety position which, in the case of a flap, can be aposition which controls deicing or demisting of the windshield of thevehicle.

At the present time, certain types of vacuum control devices must becapable of displacing an element such as a flap, for example, between atleast three positions comprising two end positions and an intermediateposition in order to ensure a sufficient degree of comfort within theoccupant compartment of the vehicle. Known devices of this type usuallycomprise a casing in which are mounted two substantially parallelmovable cups carried by diaphragms, the first cup being connected to theelement to be displaced by any suitable means. Springs are interposedrespectively between the two cups and between the second cup and abottom end-wall of the casing. Two pipes each intended to be connectedto a vacuum source and to free air open into the casing, respectivelywithin the space located between the two cups and within the spacelocated between the second cup and the bottom end-wall of the casing.

In the known technique, the two cups are positively connected to eachother by means of a coupling member which has a predetermined maximumlength and can be of the telescopic or articulated type. A first endposition of the first cup connected to the element to be displaced isobtained when the two pipes which open into the casing are connected tofree air and when the ambient pressure prevails within the casing. Inthis position, the restoring springs of both cups are unstressed. Achangeover from this first end position to an intermediate position iscarried out by producing a partial vacuum between the second cup and thebottom end-wall of the casing. This results in displacement of thesecond cup towards the bottom end-wall of the casing and in compressionof its restoring spring. The first cup follows the displacement of thesecond cup by reason of the coupling member which provides a connectionbetween them and the restoring spring of said first cup remainsunstressed. A changeover from this intermediate position to the thirdposition (the end position opposite to the first) is carried out byproducing a partial vacuum within the space located between the twocups. This results in displacement of the first cup toward the secondcup which remains in a stationary position of abutment on the bottomend-wall of the casing, and in compression of the restoring springassociated with the first cup.

Conversely, connection of the space between the two cups to free airresults in return of the first cup to the intermediate position byreason of the release of its restoring spring whereas connection to freeair of the space between the second cup and the bottom end-wall of thecasing results in return of the two cups to the first position by reasonof the release of the restoring spring associated with the second cup.

The arrangement in which a coupling member between the two cups has apredetermined maximum length and a minimum length as short as possiblenot only complicates the assembly and installation of the device butalso increases its overall size and cost.

The primary object of the invention is to overcome these disadvantagesin a vacuum control device of the general type indicated in theforegoing.

The invention is also directed to a device of this type which can beconverted very simply and very economically to a device for controllingthe displacement of an element between more than three positions.

To this end, the invention accordingly proposes a vacuum control devicefor the displacement of an element between at least three positions,comprising a casing in which are disposed at least two substantiallyparallel movable cups, the first cup being connected to the element tobe displaced. Springs are interposed respectively between the two cupsand between the second cup and a bottom end-wall of the casing. Twopipes or nipples adapted to be connected to a vacuum source and to freeair open into the casing respectively within the space located betweenthe two cups and within the space located between the second cup and thebottom end-wall of the casing. The distinctive feature of the devicelies in the fact that only the first cup is carried by a deformableflexible diaphragm attached at its periphery to the casing and havingthe function of dividing the internal space of said casing in leak-tightmanner whilst the second cup is mounted within the casing with aclearance and in a non-leaktight manner so as to be capable of movingbetween the end-wall and a fixed portion of casing against which saidcup can be applied in leak-tight manner by the associated spring,thereby dividing the internal space of the casing into two chamberswhich are separated in leak-tight manner.

Thus in the control device in accordance with the invention, the twocups no longer need to be connected by means of a coupling member havinga predetermined maximum length and the intermediate position of theelement is defined by the displacement of the first cup and thecompression of the associated restoring spring whilst the second cupremains stationary.

Furthermore, the second cup does not need to be carried by a flexibleand deformable diaphragm attached at its periphery to the casing. Thismakes it possible to achieve a further simplification in both assemblyand installation of the control device as well as to reduce its cost.

In another embodiment of the invention, the second cup is carried by aflexible and deformable diaphragm attached at its periphery to thecasing. This diaphragm extends over that face of the second cup which isdirected towards the first cup and has a central portion clamped againstthe second cup by means of a base against which the spring interposedbetween the two cups is applied.

This arrangement accordingly prevents any danger of detachment of thediaphragm from the second cup when a reduced pressure (partial vacuum)is created within the internal space of the casing between the two cupsin order that the element to be displaced may be changed-over from itsfirst position to its intermediate position, thus achieving enhancedreliability of the control device.

In accordance with another distinctive feature of the invention, thespring which is interposed between the second cup and the end-wall ofthe casing develops a force which is higher than that of the springinterposed between the two cups.

The intermediate position of the first cup and therefore of the elementto be displaced is thus defined in a wholly reliable manner.

In accordance with a further distinctive feature of the invention, thesecond cup is abuttingly applied against a fixed portion of the casingin the aforementioned first and second positions of the element to bedisplaced.

This feature makes it easier to define in a reliable manner theintermediate or second position of the element to be displaced in whichthe first cup is applied against the second cup.

Other features of the invention will be more apparent upon considerationof the following description and accompanying drawings, wherein:

FIGS. 1, 2 and 3 are longitudinal sectional views of a first embodimentof a device in accordance with the invention, this device being shown inthree different positions;

FIGS. 4, 5 and 6 are views which correspond to FIGS. 1, 2 and 3respectively, but illustrate a second embodiment of the invention.

Reference will first be made to FIGS. 1 to 3 which illustrate the firstembodiment of the device in accordance with the invention. This devicecomprises a casing consisting of two sections 10 and 12 assembledtogether by clip attachment or by means of a resilient snap-fasteningsystem in which elastically deformable arms 14 of the lower casingsection 12 cooperate by snapfastening onto an annular flange 16 of theupper casing section 10. Between said flange 16 of the upper section 10and a corresponding annular flange 18 of the lower casing section 12formed by an internal shouldered portion of said casing section areclamped the periphery 20 of a flexible and deformable diaphragm 22, anannular member 24 provided with a connecting-nipple 26 which opens intothe interior of the annular member 24 and an annular seal 28. Theannular seal 28 is placed between the flange 18 of the lower casingsection 12 and the underface of the annular member 24. The periphery 20of the diaphragm 22 is placed between the top face of the annular member24 and the flange 16 of the upper casing section 10.

A rod 32 passes in leak-tight manner through the central portion 30 ofthe diaphragm 22. Said rod extends axially upwards from the base 34 of afirst cup 36 having a substantially cylindrical or slightlyfrusto-conical skirt which is oriented in the downward direction. Saidfirst cup is applied against the underface of the diaphragm 22 and iscarried by this latter.

A second cup 38 is placed within the lower casing section 12 beneath thefirst cup 36 and has an outwardly directed bottom annular flange 40, theexternal diameter of which is smaller than the internal diameter of thelower casing section 12 and larger than the internal diameter of theflat annular seal 28 in order to be applied against this latter inleak-tight manner. A restoring spring 42 is provided betWeen the firstcup 36 and the second cup 38 in order to exert a thrust on the two cupswhich are thus continuously urged away from each other. Anotherrestoring spring 44 is placed between the second cup 38 and the bottomend-wall 46 of the lower casing section 12 in order to subject saidsecond cup to a thrust which continuously urges this latter away fromthe end-wall 46.

The base 34 of the first cup 36 has a tubular portion 48 which isoriented towards the second cup 38.

The lower casing section 12 is provided in the same manner as theannular member 24 with a nipple 50 which forms a connecting-pipe andopens into the interior of the lower casing section 12. The two nipples26 and 50 both form connecting-pipes which are intended to be connectedto a vacuum source or to free air under the control of suitable meansprovided on the dashboard of the vehicle when the device in accordancewith the invention is intended to control the displacement of a flap orlike element of an installation for heating or air-conditioning of theoccupant compartment of the vehicle. Said flap or like element ispositively connected to the rod 32 of the first cup 36.

The device in accordance with the invention operates as follows:

The position shown in FIG. 1 corresponds to a first position orend-of-travel position of the element to be displaced, this positionbeing reached when the two nipples 26 and 50 are connected to free air.Under these conditions, the ambient pressure prevails within the casingand, more specifically, within the internal space of said casing asdefined on the one hand between the first cup 36 and its diaphragm 22and on the other hand the second cup 38 as well as within the internalspace defined between the second cup 38 and the bottom end-wall 46 ofthe lower casing section 12.

In this position, the second cup 38 is thrust in the upward direction byits restoring spring 44 and its annular flange 40 is applied inleak-tight contact with the flat annular seal 28. The first cup 36 isalso thrust upward by its restoring spring 42 and comes into abutmentwith a top annular flange 52 of the upper casing section 10 through theintermediary of the central portion 30 of the diaphragm 22. Said topannular flange 52 defines an orifice through which passes the rod 32 forproviding a connection with the element to be displaced.

This first position is therefore well-defined by reason of the abuttingcontact of the two cups 36 and 38 with fixed elements of the casing ofthe device.

A changeover from this first position to the intermediate position shownin FIG. 2 is produced by connecting the nipple 26 to the vacuum sourcewhilst the nipple 50 is still open to the atmosphere. Under theseconditions, the reduced pressure (partial vacuum) maintained within theinternal space located between the first cup 36 and the second cup 38results in a displacement of the first cup 36 toward the second cup 38and in compression of the restoring spring 42 associated with the firstcup 36 until the lower tubular portion 48 of the first cup 36 comes intoabutment with the second cup 38. The second cup 38 remains in the sameposition as in FIG. 1, on the one hand by reason of the partial vacuumwhich produces action on its top face and on the other hand by reason ofthe force developed by its restoring spring 44 which is higher than theforce developed by the restoring spring 42 of the first cup 36.

The second position or intermediate position shown in FIG. 2 istherefore a stable position which is perfectly defined by reason of thefact that the first cup 36 is applied against the second cup 38 and byreason of the fact that the second cup 38 is applied against the annularseal 28.

A changeover from the intermediate position of FIG. 2 to the thirdposition or end-of-travel position shown in FIG. 3 is produced byconnecting the nipple 50 to the vacuum source whilst the nipple 26 stillremains connected to said vacuum source. The partial vacuum which thenprevails within the internal space located between the second cup 38 andthe bottom end-wall 46 of the lower casing section 12 balances thepartial vacuum which prevails within the internal space located betweenthe first cup 36 and the second cup 38. The cup 38 is no longermaintained in contact with the annular seal 28 and no longer performsits abutment function for the cup 36. As mentioned earlier, the externaldiameter of the annular flange 40 of the second cup 38 is smaller thanthe internal diameter of the lower casing section 12, with the resultthat the second cup 38 is displaceable in non-leaktight manner withinthe lower casing section 12. Since the top face of the cup 36 is stillexposed to ambient pressure and the bottom face of the cup is exposed toreduced pressure (partial vacuum), said cup 36 continues to move andaccordingly exerts a downward thrust on the second cup 38 whilecompressing the restoring spring 44 until the annular flange of saidsecond cup comes into abutment with the bottom end-wall 46 of the lowercasing section 12.

The third position of the device is also perfectly defined by reason ofthe abutting application of the second cup 38 against the bottomend-wall of the lower casing section 12 and by reason of the abuttingapplication of the first cup 36 against the second cup 38.

A changeover from the third position shown in FIG. 3 to the intermediateposition shown in FIG. 2 is obtained by connecting the nipple 50 to theatmosphere whilst the nipple 26 remains connected to the vacuum source.

Advantageously, the internal cross-sectional area of theconnecting-nipple 26 is smaller than that of the nipple 50 in order tofacilitate the establishment of ambient pressure within the lower casingsection 12 with respect to the application of a partial vacuum by meansof the connecting-nipple 26. Under these conditions, the two cups 36 and38 are returned to the intermediate position of FIG. 2 by expansion ofthe restoring spring 44 until the annular flange 40 of the second cup 38is restored to leak-tight application against the annular seal 28 whilstthe first cup 36 remains in abutting contact with the second cup 38 oris restored to abutting contact with this latter as soon as the annularflange 40 is applied against the annular seal 28.

It is then possible to change-over from the intermediate position ofFIG. 2 to the first position of FIG. 1 by connecting the nipple 26 tothe atmosphere.

A reduction of internal cross-sectional area of the connecting-nipple 26with respect to the internal cross-sectional area of theconnecting-nipple 50 can be obtained by selecting a nipple 26 having aninternal diameter which is smaller than that of the nipple 50, or bymeans of a constriction or throttled portion at any point of this nippleor of the pipe which connects this latter to the vacuum source.

The device in accordance with the invention as shown in FIGS. 1 to 3offers a number of advantages over the prior art technique, especiallythe fact that there is no connecting member between the two cups 36 and38 and the fact that the second cup 38 is not carried by a flexible anddeformable diaphragm of the same type as the diaphragm 22 which carriesthe first cup 36. Generally speaking, this device is also of smalleroverall size than known devices of the prior art.

Reference will now be made to FIGS. 4 to 6 which illustrate a secondembodiment of the invention.

In these figures, the casing of the device in accordance with theinvention consists of a top casing section 60 which is similar to theupper casing section 10 of FIGS. 1 to 3 and of an intermediate casingsection 62 of tubular shape which is open at both ends and is mounted byclip attachment or by snap-fastening onto a bottom annular flange 64 ofthe top casing section 60. Said casing also consists of a bottom casingsection 66 having a bottom end-wall 68 provided with a nipple 70 andmounted by clip attachment or snap-fastening onto a lower annular flange72 of the intermediate casing section 62.

The periphery 74 of a flexible and deformable diaphragm 76 which issimilar to the diaphragm 22 of the first embodiment is clamped betweenthe casing sections 60 and 62. Said diaphragm 76 is adapted to carry afirst cup 78 which is similar to the first cup 36 of the firstembodiment and is provided with a rod 80 or any suitable means forconnecting the device to the element to be displaced.

A second flexible and deformable diaphragm 82 is clamped at itsperiphery 84 between the casing sections 62 and 66 and is adapted tocarry a second cup 86 having a closed tubular upper portion 88 which isforcibly fitted within a central collar 90 of the diaphragm 82. Thecentral portion of said diaphragm is clamped between the second cup 86(which is applied against the underface of said diaphragm) and a tubularbase 92 applied against the top face of said diaphragm and provided witha cylindrical skirt 94 which is oriented upwards in the direction of thefirst cup 78. Said cylindrical skirt 94 has an external diameter whichis very slightly smaller than the internal diameter of the intermediatecasing section 62 in order to be capable of sliding within saidintermediate casing section and in order to form a guide for thedisplacement of the second cup 86. The tubular base 92 is mounted innon-leaktight manner within the interior of the intermediate casingsection 62 and is accordingly provided with apertures 95.

A restoring spring 98 is provided between the first cup 78 and thetubular base 92 and another restoring spring 100 is provided between thesecond cup 86 and the bottom end-wall 68 of the bottom casing section66.

The intermediate casing section 62 is provided with a nipple 96 forconnecting it either to a vacuum source or to the atmosphere.

The operation of this device is similar to that of the device shown inFIGS. 1 to 3 and takes place as follows:

A first position is illustrated in FIG. 4 in which the two nipples 70and 96 are connected to the atmosphere. Under these conditions, theambient pressure prevails within the internal space of the casing of thedevice located between the two diaphragms 76 and 82 and within theinternal space located between the diaphragm 82 and the bottom end-wall68 of the bottom casing section 66. The first cup 78 is thrust by itsrestoring spring 98 against a top annular rim 102 of the top casingsection 60 whilst the second cup 86 is thrust by its restoring spring100 against a fixed portion of the intermediate casing section 62, saidfixed portion being formed by an internal shoulder 104 of said casingsection against which is applied the upper end of the skirt 94 of thebase 92.

A changeover from this first position to the intermediate position shownin FIG. 5 is achieved by allowing the connecting-nipple 70 of the bottomcasing section 66 to remain open to the atmosphere and by connecting thenipple 96 of the intermediate casing section 62 to a vacuum source. Theestablishment of a partial vacuum within the internal space locatedbetween the diaphragms 76 and 82 results in displacement of the firstcup 78 toward the second cup 86 and in compression of the restoringspring 98, whereupon the first cup 78 comes into abutting contact withthe second cup 86. Said second cup 86 remains stationary under thecombined action of the reduced pressure on its top face and of itsrestoring spring 100 which develops a force of greater magnitude thanthat of the restoring spring 98 of the first cup 78. In thisintermediate position, the base 92 has the design function ofdetermining the position of the second cup 86 with a high degree ofaccuracy by means of the abutting application of its cylindrical skirt94 against the internal annular shoulder 104 of the intermediate casingsection 62 and also of preventing detachment of the diaphragm 82 fromthe second cup 86.

A changeover from this intermediate position to the third position shownin FIG. 6 is effected by connecting the nipple 70 of the bottom casingsection 66 to the vacuum source to which the nipple 96 of theintermediate casing section 62 remains connected. By reason of thepartial vacuum which then exists within the internal space of the casinglocated between the diaphragm 82 and the bottom end-wall 68 of thebottom casing section, the second cup 86 is in equilibrium and movesdownwards until it comes into abutting contact with the end-wall 68 ofthe bottom casing section while compressing its restoring spring 100under the thrust exerted by the first cup 78.

The device is switched back from the third position to the intermediateposition of FIG. 5 by connecting the nipple 70 to atmospheric pressurewhilst the nipple 96 remains connected to the vacuum source. Similarly,the device is switched back from the intermediate position to the firstposition shown in FIG. 4 by connecting the nipple 96 to the atmospherein the same manner as the nipple 70.

In general terms, the device in accordance with the invention thereforemakes it possible to control the displacement of any element betweenthree positions and can be very readily converted for controlling thedisplacement of the element between at least four positions. To thisend, it is only necessary in regard to the embodiment of FIGS. 1 to 3 toreplace the bottom end-wall 46 of the lower casing section 12 by anothercup of the same type as the second cup 38. This additional cup will alsobe applied against an annular seal and will also be controlled by arestoring spring supported on the end-wall of the casing or else on yetanother cup.

In regard to the embodiment of FIGS. 4 to 6, it is merely necessary toreplace the bottom end-wall 68 of the bottom casing section 66 by anadditional cup of the type just considered by way of addition to thedevice of FIGS. 1 to 3. Alternatively, said additional cup could becarried by a diaphragm in the same manner as the second cup 86 of thesecond embodiment.

What is claimed is:
 1. A vacuum control device for the displacement ofan element between at least three positions, comprising a casing inwhich are disposed at least first and second spaced substantiallyparallel movable cups, said casing having a bottom end-wall, the firstcup being connected to the element to be displaced, said second cupbeing spaced from said bottom end-wall, springs interposed respectivelybetween the two cups and between the second cup and said bottom end-wallof the casing, and two fluid communication means adapted to be connectedto a vacuum source and to atmospheric air and opening into the casingrespectively within the space located between the two cups and withinthe space located between the second cup and the bottom end-wall of thecasing, a separate flexible and deformable diaphragm carrying each cupand having a periphery attached to the casing and providing a leak-tightdivision of the internal space of said casing, the diaphragm whichcarries the second cup including a central portion with a base thereon,said base supporting the spring interposed between the two cups, saidcasing including a fixed portion remote from said bottom endwall of thecasing, the spring interposed between the second cup and the bottomend-wall biasing said second cup and base to engage said base againstsaid fixed portion and define a fixed position for said second cup.
 2. Adevice according to claim 1 wherein the two cups are without anypositive connection between them.
 3. A device according to claim 1wherein the three positions of the element to be displaced include afirst and a third end-position of the element defined respectively byapplication of ambient pressure within the casing via the two fluidcommunication means and by application of a partial vacuum within thecasing via said two fluid communication means and a second position orintermediate position defined by application of a partial vacuum solelybetween the two cups while the internal space of the casing between thesecond cup and the bottom end-wall of the casing is at ambient pressure.4. A device according to claim 1 wherein the spring interposed betweenthe second cup and the bottom end-wall of the casing develops a force ofgreater magnitude than that of the spring which is interposed betweenthe two cups.
 5. A device according to claim 3, wherein the base is inabutting contact with the aforesaid fixed portion of the casing in theaforesaid first and second positions of the element to be displaced. 6.A device according to claim 1, wherein the fixed portion of the casingagainst which said base is biased is an internal annular shoulder on thecasing.
 7. A device according to claim 1 wherein said base is movablymounted within the casing in nonleak-tight manner.